The invention relates to an identification card having information in the form of patterns, letters, numbers and/or images applied by means of a laser beam, and a method of producing same.
Identification cards in the form of credit cards, bank cards, cash payment cards and so on are used increasingly in all kinds of service sectors, cashless payments and within enterprises. Due to their extensive use they are typical mass production items, on the one hand, i.e. their production must be simple and economical; on the other hand they must be designed in such a way that they are protected against forgery and falsification to as great a degree as possible. The many sorts of identification cards already on the market and still in a stage of development testify to the efforts of the relevant industry to optimize these two contradictory conditions.
In particular, it is necessary that the data relating to the card owner which are applied during the so-called personalization of the identification card, be protected in such a way that they cannot be manipulated afterwards. One possibility which has proved very useful in practice is the embedment of a paper inlay designed as a security print in a multilayer card. The paper inlay with its authenticity features such as watermarks, safety threads, steel intaglio printing, etc., known in the production of security paper, meets the highest standards of security and is protected against all kinds of attempted forgery and falsification due to the transparent cover film.
Mainly because of their much simpler and more economical production, all-plastic cards are also used in the identification card sector, in which the identification card data and the general printed pattern are applied to the outer surface of a small plastic card which can have a multilayer construction, if desired. In various embodiments of this type of identification card the user-related data (name, account number, etc.) are impressed into the back of the identification card so as to be in relief on the front. This allows for the transfer of the personalization data onto bills, etc. by means of an ink-ribbon in the various stores.
In spite of the economic advantages of this type of all-plastic identification card, it has turned out to be particularly disadvantageous that the directly accessible printed pattern and the personalization data are relatively unprotected against attempted falsification. The impressed data are, for example, "ironed flat" by a manipulator and then imprinted over with other data. If necessary, the printed pattern can be removed with solvents available everywhere and replaced or added to by another printed pattern.
As no security techniques for all-plastic identification cards are known up to now, which are economically feasible, on the one hand, and can be checked by anyone without any auxiliary means and cannot be imitated by means of readily available devices and materials, on the other hand, the production of total forgeries is usually possible even with the most simple means.
In order to solve this problem of lacking protection against forgery and falsification, all kinds of security features have already been proposed, such as codings embedded inside the identification card that can be "read" by IR light, holographic storage methods, etc. All these techniques, however, have the great disadvantage that they cannot be checked without elaborate auxiliary means and thus are inaccessible to the man on the street.
For the same purpose all-plastic identification cards have also been proposed, in which the photo of the card owner is engraved in a color or film layer which is usually laminated onto the outer surface (published German patent Document No. 22 25 471). The engraving is done by means of a mechanical chisel which scans the surface of the card point by point, thereby producing a sort of screen image. It is obvious that this method requires elaborate mechanics which are liable to break down. The production of this type of identification card is also slow due to the mechanical scanning or engraving point by point, which proves to be very disadvantageous for mass production. A further disadvantage is that the nicks made by the chisel during the engraving of the card, which must necessarily have a certain depth, reduce the stability of the identification card. A high degree of fatigue strength under reversed bending stresses, however, is an indispensible condition for the card, especially for daily use.
In the same connection, all-plastic identification cards have also been proposed in which photographically developed pictures of the user are embedded. This type of card is, however, unsuitable for practical use due to its dependence on the photographic method, which is generally relatively unfavorable for card technology and decentral card production, because it adopts a disadvantage in the production of the identification card with a paper inlay (the application of personalization data--in this case a photo--before completion of the identification card) without being able to utilize the very positive safety aspects of the inlay identification card (security paper inlay, etc.).
Taking the safety and production aspects into account, published German patent Document No. 29 07 004 also discloses an identification card having a card inlay made of paper and a transparent cover film, in which the person-related data are inscribed in the card inlay by means of a laser beam after the cover film has been laminated on. The information can in this case be burned into the inlay, but it can also be present as discoloration of a thermosensitive coating applied to the inlay. This type of card offers a high degree of security against falsification and forgery, as the data are protected by the cover film. As the burning in of the identification card data more or less destroys the structure of the material, on the one hand, and such data must therefore be protected against direct mechanical stress, but the discoloration present in a coating is relatively easy to remove or manipulate, on the other hand, when it is directly accessible, the personalization of identification cards as described above does not appear feasible in the case of identification cards in which the data are directly accessible on the outer surface.